Fluid management is typically required for all intensive care unit (ICU) patients. In the case of critically ill patients, fluid management is an important and difficult issue. Fluid resuscitation is an initial therapeutic intervention with patients after suffering a trauma, or when symptoms of hypotension, evidence of poor organ/tissue perfusion, or other significant hemodynamic challenges are present. Fluid resuscitation refers to the medical practice of replenishing body fluids lost through perspiration, bleeding, fluid shifts, or other pathological processes. The replenishing may include introduction of fluids orally, intravenously, or otherwise.
In some cases, suboptimal administration of fluid resuscitation may lead to an increase in morbidity and mortality in critically ill patients. Therefore, fluid management, in which fluid resuscitation is coordinated with hemodynamic monitoring, is an important component of the treatment of patients requiring fluid resuscitation. Various types of hemodynamic monitors may provide physicians with measurements of various hemodynamic parameters. Such parameters may include stroke volume (the volume of blood that is pumped from the left ventricle during each heartbeat), heart rate, cardiac output, respiration rate, or other relevant hemodynamic parameters. Knowledge of the values of such parameters may assist a physician in determining whether or not fluid resuscitation is necessary, and if it is, what quantity of fluid is to be administered.
The hemodynamic monitors that are most widely used are invasive devices. For example, an invasive device may include one or more catheters or sensors that are inserted into the patient's blood vessels.
Ultrasound imaging is widely used as a tool for medical diagnostics. Ultrasound imaging may provide high-resolution images of internal organs and biological structures deep inside the body, as well as functional information, e.g., with regard to cardiac function and blood flow. A typical ultrasound transducer includes an array of elements that emit and receive ultrasonic waves. When operated in brightness mode (B-mode), an ultrasound system may generate real time two-dimensional images based on the received waves. When operated in Doppler mode, the ultrasound system may provide measurements of the velocities of blood and tissue. Doppler ultrasound may be used to estimate blood velocity by transmitting streams of high-frequency sound waves and analyzing the signals reflected from circulating red blood cells. The local velocity profile is derived from measured changes in the phase of a received signal. Doppler scans may be used in the diagnosis of such conditions as heart valve defects, congenital heart disease, artery occlusions, and aneurysms.